Many topical medications including antiseptics, analgesics, anesthetics and Platelet-Derived Growth Factor (PDGF) are applied to integument or skin to reduce tactile sensation, cause numbing or aid in the healing process. Likewise, anti-fungal medications must also be topically applied in most circumstances.
Various hand held applicators such as aerosol sprayers and squeeze bottles have been developed for topical application of liquid medical products. For many topical applications, it is desirous to atomize the liquid medication being applied. Atomization is the mechanical subdivision of liquid into drops. The atomized drops can have a wide range of sizes depending on the particular application. A spray is typically considered to be coarse drops having a size in the range of 100 to 1,000 microns in diameter. To mist a liquid is considered to be the atomization of liquid into fine drops sized in the range of 10 to 100 microns in diameter. For most topical medication applications, spraying is considered sufficient. However, it is highly desirable for the user applying the medication to have an atomization device, or sprayer, which provides good directional control of the spray and allows the medication to be applied from a distance that will not jeopardize further traumatization of the skin by inadvertent touching by the user's hand or by the sprayer itself.
Some topical pharmaceuticals and medications come commercially prepackaged in medication vials, similar in appearance to cartridges used for syringe applications, but modified as a sprayer sub-assembly. The sprayer sub-assembly includes an index finger actuated spray pump with a spray head which directs the spray from the pump at a 90.degree. axis from the longitudinal axis of the vial. One such product is marketed by Amgen Corp. of Thousand Oaks, Calif. and available from Tower (Medical) American Convertors division of American Hospital Supply Corporation under part no. 92308 (31/2".times.8") 8T89E (hereinafter "PDGF Airless Topical Applicator"). These spray sub-assemblies require the user to grasp the sprayer between the thumb and fingers and use the index finger to actuate the sprayer head in a pumping motion and discharge the medication from the sprayer to the desired surface. The actuation of the sprayer sub-assembly is similar to that used for commercially available hand held aerosol breath sprays.
There are several disadvantages with this sprayer structure. Because the spray head is used to actuate the spray pumping mechanism, the spray head must be moved, or pumped, relative to the liquid container or vial to actuate the spray mechanism. Furthermore, the head is pumped by the index finger and the spray exits from the spray head at a 90.degree. angle relative to the axis of the pumping motion and at a point immediately adjacent the user's index finger, the directional control of the spray is compromised. Unless the user compensates for the pumping motion by moving the entire spray assembly during spraying, each pump or stroke of the spray head causes the point of origin of the spray to change in location. This motion compromises the directional stability of the spray stream.
Additionally, the index finger actuated pumping structure requires the user to grasp the spray assembly in such a way that the longitudinal axis of the spray assembly must be positioned generally parallel to the surface of the skin receiving the spray. This positioning is a product of the spray exit stream being directed at a 90.degree. angle relative to the pumping axis of the sprayer. In some circumstances, the user may have to position the sprayer close to the skin to aim the spray in a particular area. This awkward positioning may cause inadvertent contact between the traumatized skin receiving the spray and the user's hand or the sprayer itself. Where sterility is concerned, this potential for contact has profound ramifications.
Accurate aiming of an index finger controlled sprayer can also be a problem. Once the user grasps the sprayer, the nozzle on the spray head faces away from the user. Due to the shape of a typical index finger actuated spray head, the user cannot be sure of the aim until spraying has begun. The first pump of the sprayer sometimes directs the spray in an undesired direction. Furthermore, users with large index fingers or improperly positioned index fingers may also deflect part of the exiting spray with the index finger protruding in front of the spray nozzle. This may also compromise aiming and sterility. Therefore, there is a need for an improved hand held topical sprayer which eliminates these and other disadvantages of prior art devices.